Display device, method of driving display device, and electronic apparatus

ABSTRACT

According to an aspect, a display device includes: a display region in which a plurality of pixels are arranged in a matrix; a plurality of signal lines that extend in a second direction in the display region; a vertical drive circuit that is coupled to first ends of the scanning lines and applies a vertical scanning pulse to the first ends to select each row of the pixels in the display region; a horizontal drive circuit that performs a display operation of supplying an image signal to each of the pixels in the row selected by the vertical drive circuit through the signal lines; and a plurality of switches that are coupled to second ends of the scanning lines respectively. Each of the switches supplies the same potential as that supplied to the first ends by the vertical drive circuit to the second end corresponding thereto in an idle period.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of application Ser. No.14/167,069, filed Jan. 29, 2014 and claims priority from JapaneseApplication No. 2013-016240, filed on Jan. 30, 2013, and JapaneseApplication No. 2014-011046, filed on Jan. 24, 2014, the contents ofwhich are incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to a display device, a method of driving adisplay device, and an electronic apparatus, and more particularly, to adisplay device, a method of driving a display device, and an electronicapparatus that have an idle period in which display is stopped betweendisplay operation periods.

2. Description of the Related Art

In recent years, attention has been paid to touch detection devicesreferred to as so-called touch panels capable of detecting externalproximity objects which approach from the outside. The touch panels aremounted on or integrated with a display device such as a liquid crystaldisplay device and are used for display devices with a touch detectionfunction. The display devices with a touch detection function displayvarious button images on the display device, thereby enabling input ofinformation with the touch panel as a substitute for ordinary mechanicalbuttons. The display devices with a touch detection function, whichinclude such touch panels, do not require input devices such as akeyboard, a mouse, and a keypad, and the use of the display devicestends to increase in portable information devices such as cellularphones as well as in computers.

Types of a touch detection method include several types such as anoptical type, a resistive type, and a capacitance type. When touchdetection devices of the capacitance type are used in mobile devices andthe like, devices having relatively simple structures and low powerconsumption can be provided. For example, in Japanese Patent ApplicationLaid-open Publication No. 2012-048295 (JP-A-2012-048295), a capacitivetouch detection device is disclosed.

In the capacitive touch detection devices, capacitance is formed betweena drive electrode and a touch detection electrode and varies inaccordance with an external proximity object which approaches from theoutside. These display devices use the variation in capacitance andanalyze a touch detection signal which appears in the touch detectionelectrode when a touch detection driving signal is applied to the driveelectrode to detect the external proximity object.

In the display devices with a touch detection function in which adisplay function and a touch detection function are integrated with eachother, for example, a touch detection operation may affect display. Incontrast, the display device with a touch detection function disclosedin JP-A-2012-048295 detects a touch in a touch detection operationperiod different from a display operation period, that is, an idleperiod in which display is stopped between display operations.Therefore, it is possible to reduce the influence of the touch detectionoperation on the display operation.

However, when the touch detection driving signal is applied to the driveelectrode, the potential of the common electrode for display may bevaried. For example, in the display device, when the common electrodefor display is also used as one of a pair of electrodes for touchsensing and the other electrode (touch detection electrode) is arrangedso as to form capacitance together with the common electrode, avariation in the potential of the common electrode for display mayincrease. Accordingly, in the idle period in which display is stoppedbetween the display operations, a variation in the potential of thecommon electrode for display becomes the noise of a scanning line due tothe capacitance between the common electrode for display and thescanning line, and the noise may cause a leakage current.

In addition, some display devices without a touch detection functionperform, in the idle period in which display is stopped between thedisplay operations, a driving operation other than a display drivingoperation, such as a drive operation in which the potential of thecommon electrode for display varies. In this case, similarly, in theidle period, the variation in the potential of the common electrode fordisplay becomes the noise of a scanning line due to the capacitancebetween the common electrode for display and the scanning line, and thenoise may cause a leakage current.

In order to suppress the influence of the noise of the scanning line dueto the variation in the potential of the common electrode for display,it is effective that a first gate driver and a second gate driver whichare arranged such that the scanning lines are interposed therebetween inthe extension direction of the scanning lines may select each row ofpixels in a display region from both ends of the scanning lines.However, transistor elements of the first and second gate drivers needto be provided in a frame which does not contribute to the displayregion. In this case, the size of the frame may increase. When the sizeof the frame increases, the space of the display region of the displaydevice is limited. Therefore, it is necessary to reduce the number oftransistor elements of the first and second gate drivers in the displaydevice.

For the foregoing reasons, there is a need for a display device, amethod of driving the display device, and an electronic apparatus thatsuppress the noise of a scanning line while suppressing the increase insize of a frame.

SUMMARY

According to an aspect, a display device includes: a display region inwhich a plurality of pixels are arranged in a matrix; a frame regionoutside the display region; a common electrode that gives a commonpotential to the corresponding pixels; a plurality of scanning linesthat extend in a first direction in the display region; a plurality ofsignal lines that extend in a second direction in the display region;first and second vertical drive circuits that are arranged in the frameregion such that the scanning lines are interposed therebetween in thefirst direction, the first and second vertical drive circuits beingconfigured to alternately apply a vertical scanning pulse in the firstdirection to select each row of the pixels in the display region; ahorizontal drive circuit that performs a display operation of supplyingan image signal to each of the pixels in the row selected by the firstvertical drive circuit or the second vertical drive circuit through thesignal lines; and a plurality of switches each of which is coupled to anend opposite to a vertical drive circuit connection end of each scanningline which is coupled to the first vertical drive circuit or the secondvertical drive circuit. The switches supply the same potential as thatsupplied to the scanning line by the first vertical drive circuit or thesecond vertical drive circuit to the scanning line in an idle period inwhich the horizontal drive circuit stops the display operation.

According to another aspect, a method is for driving a display deviceincluding: a display region in which a plurality of pixels are arrangedin a matrix; a plurality of signal lines that extend in a seconddirection in the display region; first and second vertical drivecircuits that are arranged in the frame region such that the scanninglines are interposed therebetween in the first direction, the first andsecond vertical drive circuits being configured to alternately apply avertical scanning pulse in the first direction to select each row of thepixels in the display region; a horizontal drive circuit that performs adisplay operation of supplying an image signal to each of the pixels inthe row selected by the first vertical drive circuit or the secondvertical drive circuit through the signal lines; and a plurality ofswitches each of which is coupled to an end opposite to a vertical drivecircuit connection end of each scanning line which is coupled to thefirst vertical drive circuit or the second vertical drive circuit. Themethod includes: the switches supplying the same potential as thatsupplied to the scanning line by the first vertical drive circuit or thesecond vertical drive circuit to the scanning line in an idle period inwhich the horizontal drive circuit stops the display operation.

According to another aspect, an electronic apparatus has the displaydevice.

According to another aspect, a display device includes: a display regionin which a plurality of pixels are arranged in a matrix; a frame regionoutside the display region; a plurality of scanning lines that extend ina first direction in the display region; a plurality of signal linesthat extend in a second direction in the display region; a verticaldrive circuit that is coupled to first ends of the scanning lines andapplies a vertical scanning pulse to the first ends to select each rowof the pixels in the display region; a horizontal drive circuit thatperforms a display operation of supplying an image signal to each of thepixels in the row selected by the vertical drive circuit through thesignal lines; and a plurality of switches that are coupled to secondends of the scanning lines respectively. Each of the switches suppliesthe same potential as that supplied to the first ends by the verticaldrive circuit to the second end corresponding thereto in an idle periodin which the horizontal drive circuit stops the display operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example of the configurationof a display device with a touch detection function according to anembodiment;

FIG. 2 is a diagram illustrating a state in which a finger is not incontact with or in proximity to a device for illustrating a basicprinciple of a touch detection method of a capacitance type;

FIG. 3 is a diagram illustrating an example of an equivalent circuit ina state in which a finger is not in contact with or in proximity to adevice as illustrated in FIG. 2;

FIG. 4 is a diagram illustrating a state in which a finger is in contactwith or in proximity to a device for illustrating a basic principle of atouch detection method of a capacitance type;

FIG. 5 is a diagram illustrating an example of an equivalent circuit ina state in which a finger is not in contact with or in proximity to adevice as illustrated in FIG. 4;

FIG. 6 is a diagram illustrating an example of the waveforms of adriving signal and a touch detection signal;

FIG. 7 is a diagram illustrating an example of a module provided withthe display device with a touch detection function according to theembodiment;

FIG. 8 is a cross-sectional view illustrating the schematiccross-sectional structure of the display unit with a touch detectionfunction according to the embodiment;

FIG. 9 is a diagram illustrating an example of a control device of thedisplay device with a touch detection function according to theembodiment;

FIG. 10 is a circuit diagram illustrating the arrangement of pixels inthe display unit with a touch detection function according to theembodiment;

FIG. 11 is a schematic diagram illustrating a relation between a sourcedriver and signal lines in the module provided with the display devicewith a touch detection function according to the embodiment;

FIG. 12 is a perspective view illustrating an example of theconfiguration of drive electrodes and touch detection electrodes in thedisplay unit with a touch detection function according to theembodiment;

FIG. 13 is a schematic diagram illustrating an example of a touchdetection operation of the display device with a touch detectionfunction according to the embodiment;

FIG. 14 is a schematic diagram illustrating an example of the touchdetection operation of the display device with a touch detectionfunction according to the embodiment;

FIG. 15 is a schematic diagram illustrating an example of the touchdetection operation of the display device with a touch detectionfunction according to the embodiment;

FIG. 16 is a diagram illustrating a display operation and the touchdetection operation of the display device with a touch detectionfunction according to the embodiment;

FIG. 17 is a block diagram illustrating a switch according to theembodiment;

FIG. 18 is a timing chart illustrating a display operation period and anidle period according to the embodiment;

FIG. 19 is a circuit diagram illustrating an example of a scanning line;

FIG. 20 is a circuit diagram illustrating an example of the scanningline;

FIG. 21 is a circuit diagram illustrating an example of the scanningline according to the embodiment;

FIG. 22 is a diagram illustrating a variation in the potential of thescanning line according to the embodiment;

FIG. 23 is a diagram illustrating coupling capacitance between a commonelectrode and the scanning line of the display device;

FIG. 24 is a cross-sectional view illustrating the schematiccross-sectional structure of a display unit with a touch detectionfunction according to a modification;

FIG. 25 is a diagram illustrating a variation in the potential of thescanning line according to the embodiment;

FIG. 26 is a diagram schematically illustrating common potentialinversion driving in two horizontal periods;

FIG. 27 is a diagram illustrating an example of an electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 28 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 29 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 30 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 31 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 32 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 33 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 34 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 35 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 36 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 37 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied;

FIG. 38 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied; and

FIG. 39 is a diagram illustrating an example of the electronic apparatusto which the display device with a touch detection function or thedisplay device according to the embodiment is applied.

DETAILED DESCRIPTION

Modes for carrying out the present disclosure (embodiments) will bedescribed in detail with reference to the drawings. However, the presentdisclosure is not limited to the contents described in the followingembodiments. Each constituent element described below includes elementsthat can be easily conceived by those skilled in the art, elements thatare substantially identical thereto. Further, the constituent elementsdescribed below may be appropriately combined. The description will bepresented in the following order.

1. Embodiment

-   -   1-1. Display Device with Touch Detection Function    -   1-2. Display Device

2. Application Examples (Electronic Apparatuses)

-   -   Examples in which Display Device according to Embodiment Is        Applied to Electronic Apparatus

3. Aspects of Disclosure

1. Embodiment 1-1. Display Device with Touch Detection Function

1-1A. Example of Configuration

Example of Overall Configuration

FIG. 1 is a block diagram illustrating an example of the configurationof a display device with a touch detection function according to anembodiment. The display device 1 with a touch detection functionincludes a display unit 10 with a touch detection function, a controlunit 11, a gate driver 12, a source driver 13, a source selector unit13S, a drive electrode driver 14, and a touch detection unit 40. Thedisplay device 1 with a touch detection function is a display device iswhich the display unit 10 with a touch detection function has a touchdetection function. The display unit 10 with a touch detection functionis a device in which a liquid crystal display unit 20 using a liquidcrystal display element as a display element is integrated with acapacitive touch detection device 30. The display unit 10 with a touchdetection function may be a device in which the capacitive touchdetection device 30 is mounted on the liquid crystal display unit 20which uses the liquid crystal display element as the display element.

The liquid crystal display unit 20 sequentially scans horizontal linesone by one in response to scanning signals Vscan supplied from the gatedriver 12 to perform display, as described later. The control unit 11 isa circuit that supplies control signals to the gate driver 12, thesource driver 13, the drive electrode driver 14, and the touch detectionunit 40 on the basis of a video signal Vdisp supplied from the outsidesuch that the gate driver 12, the source driver 13, the drive electrodedriver 14, and the touch detection unit 40 operate in synchronizationwith each other. In the present disclosure, a control device includesthe control unit 11, the gate driver 12, the source driver 13, and thedrive electrode driver 14.

The gate driver 12 has a function of sequentially selecting onehorizontal line to be driven from among horizontal lines of the displayunit 10 with a touch detection function, on the basis of the controlsignal supplied from the control unit 11.

The source driver 13 is a circuit which supplies a pixel signal Vpix toeach pixel Pix (sub-pixel SPix) (which will be described later) of thedisplay unit 10 with a touch detection function on the basis of thecontrol signal supplied from the control unit 11. The source driver 13performs time-division multiplexing for the pixel signals Vpix for aplurality of sub-pixels SPix of the liquid crystal display unit 20 togenerate pixel signals from a video signal Vdisp corresponding to onehorizontal line and supplies the generated pixel signals to the sourceselector unit 13S, as described later. In addition, the source driver 13generates a selector switch control signal Vsel required to separate thepixel signals Vpix multiplexed into a pixel signal Vsig and supplies theselector switch control signal Vsel and the pixel signal Vsig to thesource selector unit 13S. This multiplexing allows the number of linesbetween the source driver 13 and the source selector unit 13S to bereduced.

The drive electrode driver 14 is a circuit which supplies a touchdetection driving signal (hereinafter, also referred to as a touchdriving signal) VcomAC and a display driving voltage VCOM, which is adisplay voltage, to a drive electrode COML, which will be describedlater, of the display unit 10 with a touch detection function, on thebasis of the control signal supplied from the control unit 11.

The touch detection unit 40 is a circuit which detects whether the touchdetection device 30 is touched (in the above-mentioned touch or approachstate) or not, on the basis of the control signal supplied from thecontrol unit 11 and a touch detection signal Vdet supplied from thetouch detection device 30 of the display unit 10 with a touch detectionfunction. When the touch detection device 30 is touched, the touchdetection unit 40 calculates, for example, the coordinates of a touchpoint in a touch detection region. The touch detection unit 40 includesa touch detection signal amplifier 42, an A/D conversion unit 43, asignal processing unit 44, a coordinate extracting unit 45, and adetection timing control unit 46.

The touch detection signal amplifier 42 amplifies the touch detectionsignal Vdet supplied from the touch detection device 30. The touchdetection signal amplifier 42 may include a low-pass analog filter whichremoves a high-frequency component (noise component) included in thetouch detection signal Vdet, and extracts a touch component to outputthe touch component.

Basic Principle of Capacitive Touch Detection

The touch detection device 30 operates on the basis of the basicprinciple of capacitive touch detection and outputs the touch detectionsignal Vdet. The basic principle of the touch detection of the displaydevice 1 with a touch detection function according to the embodimentwill be described with reference to FIGS. 1 to 6. FIG. 2 is a diagramillustrating a state in which a finger is not in contact with or inproximity to a device for illustrating a basic principle of a touchdetection method of a capacitance type. FIG. 3 is a diagram illustratingan example of an equivalent circuit in a state in which a finger is notin contact with or in proximity to a device as illustrated in FIG. 2.FIG. 4 is a diagram illustrating a state in which a finger is in contactwith or in proximity to a device for illustrating a basic principle of atouch detection method of a capacitance type. FIG. 5 is a diagramillustrating an example of an equivalent circuit in a state in which afinger is not in contact with or in proximity to a device as illustratedin FIG. 4. FIG. 6 is a diagram illustrating an example of the waveformsof the driving signal and the touch detection signal.

For example, as illustrated in FIG. 2, a capacitive element C1 includesa pair of electrodes, that is, a drive electrode E1 and a touchdetection electrode E2 which face each other with a dielectric Dinterposed therebetween. As illustrated in FIG. 3, the capacitiveelement C1 includes one end coupled to an AC signal source (drivingsignal source) S and the other end coupled to a voltage detector (touchdetection unit) DET. The voltage detector DET is, for example, anintegration circuit which is included in the touch detection signalamplifier 42 illustrated in FIG. 1.

When an AC square wave Sg with a predetermined frequency (for example, afrequency of about several kilohertz to several hundreds of kilohertz)is applied from the AC signal source S to the drive electrode E1 (oneend of the capacitive element C1), an output waveform (touch detectionsignal Vdet) appears through the voltage detector DET coupled to thetouch detection electrode E2 (the other end of the capacitive elementC1). The AC square wave Sg corresponding to a driving signal VcomAC.

In the state (non-contact state) in which the finger is not in contactwith (or in proximity to) a device, as illustrated in FIGS. 2 and 3, acurrent I₀ corresponding to the capacitance value of the capacitiveelement C1, in accordance with the charge and discharge of thecapacitive element C1. As illustrated in FIG. 6, the voltage detectorDET converts a variation in the current I₀ corresponding to the ACsquare wave Sg into a variation in voltage (a waveform V₀ represented bya solid line).

On the other hand, in the state (contact state) in which the finger isin contact with (or in proximity to) a device, as illustrated in FIG. 4,a capacitance C2 which is formed by the finger comes into contact withthe touch detection electrode E2 or it is adjacent to the touchdetection electrode E2. Therefore, the capacitance corresponding to afringe between the drive electrode E1 and the touch detection electrodeE2 is shielded, and thus the capacitive element C1 acts as a capacitiveelement C1′ with a less capacitance value less. In the equivalentcircuit illustrated in FIG. 5, a current I₁ flows to the capacitiveelement C1′. As illustrated in FIG. 6, the voltage detector DET convertsa variation in the current I₁ corresponding to the AC square wave Sginto a variation in voltage (a waveform V₁ represented by a dottedline). In this case, the amplitude of the waveform V₁ is less than thatof the waveform V₀. Therefore, the absolute value |ΔV| of a voltagedifference between the waveform V₀ and the waveform V₁ varies inaccordance with the influence of an object, such as a finger, whichapproaches from the outside. It is preferable that a period Reset inwhich the charge and discharge of a capacitor is reset by switching inthe circuit according to the frequency of the AC square wave Sg beprovided in the operation of the voltage detector DET, in order toaccurately detect the absolute value |ΔV| of the voltage differencebetween the waveform V₀ and the waveform V₁.

The touch detection device 30 illustrated in FIG. 1 sequentially scansdetection blocks one by one to perform touch detection, in response tothe driving signal Vcom (driving signal VcomAC) supplied from the driveelectrode driver 14.

The touch detection device 30 outputs the touch detection signal Vdetfor each detection block from a plurality of touch detection electrodesTDL, which will be described later, through the voltage detector DETillustrated in FIGS. 3 and 5 and supplies the detection signal Vdet tothe A/D conversion unit 43 of the touch detection unit 40.

The A/D conversion unit 43 is a circuit which samples an analog signaloutput from the touch detection signal amplifier 42 in synchronizationwith the driving signal VcomAC and converts the analog signal to adigital signal.

The signal processing unit 44 includes a digital filter which reduces afrequency component (noise component) other than the frequency at whichthe driving signal VcomAC is sampled in the output signal from the A/Dconversion unit 43. The signal processing unit 44 is a logic circuitwhich detects whether the touch detection device 30 is touched or not,on the basis of the output signal from the A/D conversion unit 43. Thesignal processing unit 44 performs a process of extracting only avoltage difference caused by the finger. The voltage difference causedby the finger is the absolute value |ΔV| of the difference between thewaveform V₀ and the waveform V₁. The signal processing unit 44 mayaverage the absolute value |ΔV| per detection block to calculate theaverage value of the absolute values |ΔV|. The signal processing unit 44can thereby reduce the influence of noise. The signal processing unit 44compares the voltage difference caused by the detected finger with apredetermined threshold voltage and determines that the object whichapproaches from the outside is in the contact state when the voltagedifference is equal to or more than the threshold voltage. On the otherhand, the signal processing unit 44 determines that the object whichapproaches from the outside is in the non-contact state when the voltagedifference is less than the threshold voltage. In this way, the touchdetection unit 40 can perform touch detection.

The coordinate extracting unit 45 is a logic circuit which calculatesthe touch panel coordinates of a touch when the signal processing unit44 detects a touch. The detection timing control unit 46 performscontrol such that the A/D conversion unit 43, the signal processing unit44, and the coordinate extracting unit 45 operate in synchronization.The coordinate extracting unit 45 outputs the touch panel coordinates asa signal output Vout.

Module

FIG. 7 is a diagram illustrating an example of a module mounted with thedisplay device with a touch detection function according to theembodiment. As illustrated in FIG. 7, the display device 1 with a touchdetection function includes a pixel substrate 2 (TFT substrate 21) and aflexible printed circuit board T. The pixel substrate 2 (TFT substrate21) has a chip-on-glass (COG) 19 mounted thereon and includes a displayregion Ad of the liquid crystal display unit 20 and frames Gd. The COG19 is an IC driver chip mounted on the TFT substrate 21 and is a controldevice provided with circuits required for a display operation, such asthe control unit 11 and the source driver 13 illustrated in FIG. 1. Inthe embodiment, the source driver 13 and the source selector unit 13Sare formed on the TFT substrate 21. The source driver 13 and the sourceselector unit 13S may be provided in the COG 19. Drive electrodescanning units 14A and 14B which are parts of the drive electrode driver14 are formed on the TFT substrate 21. The gate driver 12 is formed asgate drivers 12A and 12B on the TFT substrate 21. In the display device1 with a touch detection function, circuits, such as the drive electrodescanning units 14A and 14B and the gate driver 12, may be provided inthe COG 19.

As illustrated in FIG. 7, drive electrode blocks B of the driveelectrode COML and touch detection electrodes TDL are formed so as tointersect each other in a direction vertical to the surface of the TFTsubstrate 21.

The drive electrode COML is divided into a plurality of stripe-shapedelectrode patterns which extend in one direction. When a touch detectionoperation is performed, the drive electrode driver 14 sequentiallysupplies the driving signal VcomAC to each electrode pattern. Electrodepatterns which are supplied with the driving signal VcomAC at the sametime, among the plurality of stripe-shaped electrode patterns of thedrive electrode COML, correspond to one drive electrode blocks Billustrated in FIG. 7. The drive electrode blocks B (drive electrodeCOML) extend along the first side of the display unit 10 with a touchdetection function and the touch detection electrodes TDL extend alongthe second side of the display unit 10 with a touch detection function.The first side and the second side extend in directions different fromeach other. The output portion of the touch detection electrodes TDL isprovided, for example, in an end portion bear the second side of thedisplay unit 10 with a touch detection function and is coupled to thetouch detection unit 40 mounted on the flexible printed circuit board Tthrough the flexible printed circuit board T. As such, the touchdetection unit 40 is mounted on the flexible printed circuit board T andis coupled to each of the plurality of touch detection electrodes TDLwhich are provided in parallel to each other. The flexible printedcircuit board T is not limited to a flexible printed circuit board, butmay be a terminal. In this case, the touch detection unit 40 is providedoutside the module.

A driving signal generating unit, which will be described later, isprovided in the COG 19. The source selector unit 13S is formed by usinga TFT element and is provided in the vicinity of the display region Adon the TFT substrate 21. A plurality of pixels Pix (sub-pixels SPix),which will be described below, are arranged in a matrix (in row/columnpattern) in the display region Ad. The frames Gd are regions in whichthe pixel Pix is not arranged, when viewed from the direction verticalto the surface of the TFT substrate 21. The gate driver 12 and the driveelectrode scanning units 14A and 14B of the drive electrode driver 14are arranged in the frames Gd.

The gate driver 12 includes gate drivers 12A and 12B, and is formed byusing a plurality of TFT elements on the TFT substrate 21. The gatedrivers 12A and 12B are configured to alternately drive the displayregion Ad from one side in the direction (scanning direction) in whichthey face each other with the display region Ad interposed therebetween.In the following description, the gate driver 12A is referred to as afirst gate driver 12A and the gate driver 12B is referred to as a secondgate driver 12B. Scanning lines GCL, which will be described below, arearranged between the first gate driver 12A and the second gate driver12B. Therefore, the scanning lines GCL are provided so as to extend inparallel to the extension direction of the drive electrode COML, in thedirection vertical to the surface of the TFT substrate 21.

The drive electrode scanning units 14A and 14B are formed by using TFTelements on the TFT substrate 21. The drive electrode scanning units 14Aand 14B are supplied with the display driving voltage VCOM from thedriving signal generating unit through lines LDC for display andsupplied with the driving signal VcomAC from the driving signalgenerating unit through lines LAC for touch. The drive electrodescanning units 14A and 14B occupy a predetermined width Gdv of the frameGd, respectively. The drive electrode scanning units 14A and 14B areconfigured to drive the plurality of drive electrode blocks B which areprovided in parallel to each other from both sides. The line LDC fordisplay through which the display driving voltage VCOM is supplied andthe line LAC for touch through which the touch driving signal VcomAC issupplied are arranged in parallel in each of the frames Gd. The line LDCfor display is arranged closer to the display region Ad than the lineLAC for touch. This configuration enables the display driving voltageVCOM supplied through the line LDC for display to stabilize thepotential state of the ends of the display region Ad. Therefore, displayis stabilized, in particular, in a liquid crystal display unit usinghorizontal electric field mode liquid crystal.

The display device 1 with a touch detection function illustrated in FIG.7 outputs the touch detection signal Vdet from one side of the displayunit 10 with a touch detection function. Therefore, in the displaydevice 1 with a touch detection function, it is easy to perform wiringupon connecting the display unit 10 with a touch detection function tothe touch detection unit 40 through the flexible printed circuit board Twhich is a terminal portion.

Display Unit with Touch Detection Function

An example of the structure of the display unit 10 with a touchdetection function will be described. FIG. 8 is a cross-sectional viewillustrating the schematic cross-sectional structure of the display unitwith a touch detection function according to the embodiment. FIG. 9 is adiagram illustrating an example of the control device of the displaydevice with a touch detection function according to the embodiment. FIG.10 is a circuit diagram illustrating the arrangement of the pixels inthe display unit with a touch detection function according to theembodiment.

As illustrated in FIG. 8, the display unit 10 with a touch detectionfunction includes the pixel substrate 2, a counter substrate 3 whichfaces the pixel substrate 2 in a direction vertical to the surface ofthe pixel substrate 2, and a liquid crystal layer 6 which is providedbetween the pixel substrate 2 and the counter substrate 3.

The liquid crystal layer 6 modulates light passing therethroughaccording to the state of the electric fields, and, for example, aliquid crystal display unit using horizontal electric field mode liquidcrystal such as fringe field switching (FFS) mode or in-plane switching(IPS) mode is used as the liquid crystal layer 6. An orientation filmmay be provided between the liquid crystal layer 6 and the pixelsubstrate 2, and between the liquid crystal layer 6 and the countersubstrate 3 illustrated in FIG. 8, respectively.

The counter substrate 3 includes a glass substrate 31 and a color filter32 which is formed on one surface of the glass substrate 31. The touchdetection electrodes TDL, which are detection electrodes of the touchdetection device 30, are formed on the other surface of the glasssubstrate 31 and a polarizing plate 35 is provided on the touchdetection electrodes TDL.

The pixel substrate 2 includes the TFT substrate 21 which serves as acircuit board, a plurality of pixel electrodes 22 which are arranged ina matrix on the TFT substrate 21, a plurality of drive electrodes COMLformed between the TFT substrate 21 and the pixel electrodes 22, and aninsulating layer 24 which insulates the pixel electrodes 22 and thedrive electrodes COML from each other.

Example of System Configuration of Display device

The pixel substrate 2 includes the display region Ad, the COG 19 havingthe functions of an interface (I/F) and a timing generator, the firstgate driver 12A, the second gate driver 12B, and the source driver 13which are provided on the TFT substrate 21. The flexible printed circuitboard T illustrated in FIG. 7 transmits an external signal to the COG 19and power for driving the COG 19. The pixel substrate 2 includes thedisplay region Ad, the source driver (horizontal drive circuit) 13, andthe gate drivers (vertical drive circuits) 12A and 12B. The displayregion Ad is provided on the surface of the TFT substrate 21 which is atransparent insulating substrate (for example, a glass substrate), andin the display region Ad a plurality of sub-pixels (pixels) eachincluding a liquid crystal element are arranged in a matrix. The gatedrivers (vertical drive circuits) 12A and 12B are the first gate driver12A and the second gate driver 12B and are arranged such that thedisplay region Ad is interposed therebetween.

The display region Ad has a matrix structure in which the sub-pixelsSPix each including a liquid crystal element are arranged in a matrix ofM rows and N columns. In this specification, the row means a pixel rowincluding N sub-pixels SPix which are arranged in one direction. Inaddition, the column means a pixel column including M sub-pixels SPixwhich are arranged in a direction perpendicular to the direction inwhich sub-pixels SPix are arranged in the row. The values of M and N aredetermined by a display resolution in the vertical direction and adisplay resolution in the horizontal direction. In the display regionAd, which is the arrangement of M×N sub-pixels SPix, scanning linesGCL₁, GCL₂, GCL₃, . . . GCL_(M) are arranged for each row of sub-pixelsand signal lines SGL₁, SGL₂, SGL₃, SGL₄, SGL₅, . . . SGL_(N) arearranged for each column of sub-pixels. Hereinafter, in the embodiment,in some cases, the scanning lines GCL₁, GCL₂, GCL₃, . . . are referredto as the scanning lines GCL and the signal lines SGL₁, SGL₂, SGL₃,SGL₄, SGL₅, . . . are referred to as the lines SGL. Further, in theembodiment, any three optical scanning lines of the scanning lines GCL₁,GCL₂, GCL₃, . . . GCL_(M) may be referred to as the scanning linesGCL_(m), GCL_(m+1), GCL_(m+2) (m is a natural number and satisfies m≦M−2(m is equal to or less than M−2)), and any three optical scanning linesof the signal lines SGL₁, SGL₂, . . . SGL_(N) may be referred to as thesignal lines SGL_(n), SGL_(n+1), SGL_(n+2) (n is a natural number andsatisfies n≦N−2 (n is equal to or less than N−2)).

A master clock, a horizontal synchronization signal, and a verticalsynchronization signal, which are external signals, are input to thepixel substrate 2 from the outside and then supplied to the COG 19. TheCOG 19 converts (increase) levels of the master clock, the horizontalsynchronization signal, and the vertical synchronization signal with thevoltage amplitude of an external power supply into the voltage amplitudeof an internal power supply required to drive the liquid crystal, andsupplies a timing generator with the converted signals as the masterclock, the horizontal synchronization signal, and the verticalsynchronization signal. Thus, the COG 19 generates a vertical startpulse VST, a vertical clock pulse VCK, a switch control signal GCK, ahorizontal start pulse HST, and a horizontal clock pulse HCK. The COG 19supplies the first gate driver 12A and the second gate driver 12B withthe vertical start pulse VST, the vertical clock pulse VCK, and theswitch control signal GCK, and supplies the source driver 13 with thehorizontal start pulse HST and the horizontal clock pulse HCK. The COG19 generates the display driving voltage VCOM which is commonly suppliedto the pixel electrodes of each sub-pixel SPix and is called commonpotential, and supplies the display driving voltage VCOM to the driveelectrode COML.

The first gate driver 12A and the second gate driver 12B include atransmission circuit 61 and a buffer circuit 62, as illustrated in FIG.17. The transmission circuit 61 constitutes a shift register and mayinclude a latch circuit. The first gate driver 12A and the second gatedriver 12B generate a vertical scanning pulse from the vertical startpulse VST and the vertical clock pulse VCK and supply the verticalscanning pulse to the scanning lines GCL to sequentially select each rowof the sub-pixels SPix. The first gate driver 12A and the second gatedriver 12B are arranged such that the scanning lines GCL are interposedtherebetween in the extension direction of the scanning lines GCL. Thefirst gate driver 12A and the second gate driver 12B sequentially outputthe pulse from the upper side of the display region Ad, that is, thestart side in the vertical scanning direction to the lower side of thedisplay region Ad, that is, the end side in the vertical scanningdirection. The first gate driver 12A and the second gate driver 12Balternately apply the vertical scanning pulse in the arrangementdirection (scanning direction) of the scanning lines GCL to select eachrow of the sub-pixels SPix in the display region Ad. The first gatedriver 12A and the second gate driver 12B, which are arranged at theends of the scanning lines GCL in the longitudinal directionrespectively, alternately apply the vertical scanning pulse to everyother row of the scanning lines GCL to select each row of pixels in thedisplay region Ad. Each of the first gate driver 12A and the second gatedriver 12B is coupled to one end of scanning lines GCL in thelongitudinal direction. Accordingly, it is possible to reduce the numberof transistor elements, as compared to the case in which the first gatedriver 12A and the second gate driver 12B are coupled to both ends ofthe scanning lines GCL in the longitudinal direction. Consequently, thedisplay device 1 with a touch detection function can reduce the area ofthe frames Gd.

For example, 6-bit R (red), G (green), and B (blue) digital imagesignals Vsig are supplied to the source driver 13. The source driver 13writes display data to the sub-pixels SPix of the row which is selectedby the vertical scanning operation of the first gate driver 12A and thesecond gate driver 12B through the signal lines SGL in a pixel-by-pixelmanner, by pixels, or all at once.

Thin film transistor (TFT) elements Tr of each sub-pixel SPixillustrated in FIG. 10 and lines illustrated in FIGS. 9 and 10, such asthe signal lines SGL through which the pixel signal Vpix is supplied toeach pixel electrode 22 and the scanning lines GCL used to drive the TFTelements Tr, are formed on the TFT substrate 21. As such, the signallines SGL extend on the plane parallel to the surface of the TFTsubstrate 21 and supply the pixel signals Vpix for displaying an imageto the pixels. The liquid crystal display unit 20 illustrated in FIG. 10includes a plurality of sub-pixels SPix which are arranged in a matrix.Each of the sub-pixels SPix includes the TFT elements Tr and a liquidcrystal element LC. The TFT element Tr is formed of a thin filmtransistor. In this example, the TFT element Tr is formed of ann-channel metal oxide semiconductor (MOS) TFT. Further, the TFT elementTr may be formed of a p-channel TFT or a CMOS-TFT. One of a source or adrain of the TFT element Tr is coupled to the signal line SGL, a gate iscoupled to the scanning line GCL, and the other of the source and thedrain is coupled to one end of the liquid crystal element LC. Forexample, the one end of the liquid crystal element LC is coupled to thedrain of the TFT element Tr and the other end thereof is coupled to thedrive electrode COML.

The first gate driver 12A and the second gate driver 12B illustrated inFIG. 9 apply the vertical scanning pulse to the gate of the TFT elementsTr of the sub-pixels SPix through the scanning line GCL illustrated inFIG. 10 to sequentially select, as a display driving target, one row(one horizontal line) of the sub-pixels SPix among the sub-pixels SPixwhich are arranged in a matrix in the display region Ad. The sourcedriver 13 supplies the pixel signal Vpix to each of the sub-pixels SPixincluded in one horizontal line which is sequentially selected by thefirst gate driver 12A and the second gate driver 12B through the signalline SGL. Then, display is performed in one horizontal line of thesub-pixels SPix in response to the supplied pixel signal Vpix. The driveelectrode driver 14 applies the display driving signal (display drivingvoltage VCOM) to drive the drive electrode COML.

As described above, in the display device 1 with a touch detectionfunction, the first gate driver 12A and the second gate driver 12B drivethe scanning lines GCL_(m), GCL_(m+1), and GCL_(m+2) in a sequentiallyscanning manner to sequentially select one horizontal line. Further, inthe display device 1 with a touch detection function, the source driver13 supplies the pixel signals Vpix to the sub-pixels SPix belonging toone horizontal line and display is performed for each horizontal line.When the display operation is performed, the drive electrode driver 14applies the driving signal Vcom to the drive electrode COMLcorresponding to the horizontal line.

In the color filter 32 illustrated in FIG. 8, for example, color regionsof red (R), green (G), and blue (B) color filters are cyclicallyarranged and are associated with sub-pixels SPix illustrated in FIG. 10in a manner such that a set of R, G, and B color regions of 32R, 32G,and 32B (see FIG. 10) corresponds to a pixel Pix. The color filter 32faces the liquid crystal layer 6 in a direction perpendicular to the TFTsubstrate 21. As such, the sub-pixel SPix can display a single color.When the color regions have colors different from the above-mentionedcolors, the color filter 32 may be a combination of different colors.The color filter 32 may not be provided. A region in which the colorfilter 32 is not provided, that is, a transparent sub-pixel SPix may beprovided.

The sub-pixel SPix illustrated in FIG. 10 is coupled to other sub-pixelsSPix which belong to the same row of the liquid crystal display unit 20by the scanning line GCL. The scanning line GCL is coupled to the gatedriver 12 and the gate driver 12 supplies a scanning signal Vscan to thescanning line GCL. The sub-pixel SPix is coupled to other sub-pixelsSPix which belong to the same column of the liquid crystal display unit20 by the signal line SGL. The signal line SGL is coupled to the sourcedriver 13 and the source driver 13 supplies the pixel signal Vpix to thesignal line SGL.

FIG. 11 is a schematic diagram illustrating the relation between thesource driver and the signal lines in the module provided with thedisplay device with a touch detection function according to theembodiment. As illustrated in FIG. 11, in the display device 1 with atouch detection function, the signal lines SGL are coupled to the sourcedriver 13 provided in the COG 19 through the source selector unit 13S.The source selector unit 13S performs the on/off (switching) operationin response to the selector switch control signal Vsel.

As illustrated in FIG. 11, the source driver 13 generates the pixelsignal Vpix on the basis of the image signal Vsig and the source drivercontrol signal supplied from the control unit 11 and outputs the pixelsignal Vpix. The source driver 13 generates pixel signals each of whichis obtained by time-division-multiplexing pixel signal Vpix for aplurality of (in this example, three) sub-pixels SPix of the liquidcrystal display unit 20 of the display unit 10 with a touch detectionfunction from the image signal Vsig corresponding to one horizontalline, and supplies the multiplexed pixel signals (image signals Vsig) tothe source selector unit 13S. Further, the source driver 13 generates aselector switch control signal Vsel (VselR, VselG, and VselB) requiredto separate the pixel signals Vpix multiplexed into each image signalVsig and supplies the selector switch control signal Vsel and the imagesignals Vsig to the source selector unit 13S. This multiplexing makes itpossible to reduce the number of lines between the source driver 13 andthe source selector unit 13S.

The source selector unit 13S separates the pixel signals Vpixtime-division-multiplexed into each image signal Vsig on the basis ofthe image signals Vsig and the selector switch control signal Vselsupplied from the source driver 13 and supplies the pixel signals Vpixto the liquid crystal display unit 20 of the display unit 10 with atouch detection function.

The source selector unit 13S includes, for example, three switches SWR,SWG, and SWB. One ends of the three switches SWR, SWG, and SWB arecoupled to each other and the image signal Vsig is supplied from thesource driver 13 to the switches SWR, SWG, and SWB. The other ends ofthe three switches SWR, SWG, and SWB are coupled to the sub-pixels SPixthrough the signal lines SGL of the liquid crystal display unit 20 ofthe display unit 10 with a touch detection function. The three switchesSWR, SWG, and SWB are controlled to be turned on and off (switched) bythe selector switch control signal Vsel (VselR, VselG, and VselB)supplied from the source driver 13. This configuration enables thesource selector unit 13S to sequentially time-divisionally turn on theswitches SWR, SWG, and SWB in response to the selector switch controlsignal Vsel. Thus, the source selector unit 13S separates the pixelsignals Vpix (VpixR, VpixG, and VpixB) from the multiplexed image signalVsig. Then, the source selector unit 13S supplies the pixel signals Vpixto the three sub-pixels SPix, respectively. The red (R), green (G), andblue (B) color regions 32R, 32G, and 32B correspond to the sub-pixelsSPix, respectively. Therefore, the pixel signal VpixR is supplied to thesub-pixel SPix corresponding to the color region 32R. The pixel signalVpixG is supplied to the sub-pixel SPix corresponding to the colorregion 32G. The pixel signal VpixB is supplied to the sub-pixel SPixcorresponding to the color region 32B.

The sub-pixel SPix is coupled to other sub-pixels SPix which belong tothe same row of the liquid crystal display unit 20 by the driveelectrode COML. The drive electrode COML is coupled to the driveelectrode driver 14 and the drive electrode driver 14 supplies thedisplay driving voltage VCOM to the drive electrode COML. That is, inthis example, a plurality of sub-pixels SPix belonging to the same rowshare the drive electrode COML.

The gate driver 12 illustrated in FIG. 1 applies the scanning signalVscan to the gate of the TFT elements Tr of the sub-pixel SPix throughthe scanning line GCL illustrated in FIG. 10 to sequentially select onerow (one horizontal line) of the sub-pixels SPix among the sub-pixelsSPix which are arranged in a matrix in the liquid crystal display unit20 as a display driving target. The source driver 13 illustrated in FIG.1 supplies the pixel signal Vpix to each of the sub-pixels SPix formingthe one horizontal line which is sequentially selected by the gatedriver 12 through the signal line SGL illustrated in FIG. 10. Then,display is performed for one horizontal line of the sub-pixels SPix inresponse to the supplied pixel signals Vpix. The drive electrode driver14 illustrated in FIG. 1 applies the driving signal Vcom to drive thedrive electrodes COML in each drive electrode block B which includes apredetermined number of drive electrodes COML illustrated in FIGS. 7 and12. The drive electrode block B may include a single drive electrodeCOML or a plurality of drive electrodes COML.

As described above, the liquid crystal display unit 20 is driven suchthat the gate driver 12 sequentially time-divisionally scans thescanning lines GCL to sequentially select one horizontal line. In theliquid crystal display unit 20, the source driver 13 supplies the pixelsignals Vpix to the sub-pixels SPix belonging to one horizontal linesuch that display is performed for each horizontal line. When thisdisplay operation is performed, the drive electrode driver 14 appliesthe display driving voltage VCOM to the drive electrode block Bincluding the drive electrodes COML corresponding to the one horizontalline.

The drive electrode COML according to the embodiment functions as thedrive electrode of the liquid crystal display unit 20 and also functionsas the drive electrode of the touch detection device 30. FIG. 12 is aperspective view illustrating an example of the configuration of thedrive electrodes and the touch detection electrodes of the display unitwith a touch detection function according to the embodiment. The driveelectrodes COML illustrated in FIG. 12 face the pixel electrodes 22 inthe direction perpendicular to the surface of the TFT substrate 21, asillustrated in FIG. 8. The touch detection device 30 is configured bythe drive electrodes COML provided in the pixel substrate 2 and thetouch detection electrodes TDL provided in the counter substrate 3. Thetouch detection electrodes TDL have a stripe-shaped electrode patternwhich extends in a direction intersecting a direction in which theelectrode patterns of the drive electrodes COML extend. The touchdetection electrodes TDL face the drive electrodes COML in the directionperpendicular to the surface of the TFT substrate 21. Each electrodepattern of the touch detection electrode TDL is coupled to the input ofthe touch detection signal amplifier 42 of the touch detection unit 40.Capacitance is generated at the intersections of the electrode patternsof the drive electrodes COML and the touch detection electrode TDL. Inthe embodiment, the touch detection electrode TDL and the driveelectrode COML (drive electrode block) are divided into a plurality ofstripe-shaped portions. However, the embodiment is not limited thereto.For example, at least one of the touch detection electrode TDL and/orthe drive electrode COML (drive electrode block) may have a comb shape.Alternatively, the touch detection electrode TDL and/or the driveelectrode COML (drive electrode block) may be divided into a pluralityof portions and the shape of a slit to divide the drive electrode COMLmay have a straight line or a curved line.

According to this configuration, when the touch detection device 30performs the touch detection operation, the drive electrode driver 14 isdriven to time-divisionally perform line-sequential scanning for thedrive electrode blocks B illustrated in FIG. 7. Then, the driveelectrode block B (one detection block) to be applied with the driveelectrodes COML is sequentially selected in the scanning direction Scan.Then, the touch detection device 30 outputs the touch detection signalsVdet from the touch detection electrodes TDL. As such, the touchdetection device 30 performs touch detection for one detection block.

FIGS. 13 to 15 are schematic diagrams illustrating examples of the touchdetection operation of the display device with a touch detectionfunction according to the embodiment. FIG. 16 is a diagram illustratingthe display operation and touch detection operation of the displaydevice with a touch detection function according to the embodiment. Inthe drawing, an operation of applying the touch driving signal VcomAC toeach of drive electrode blocks B1 to B20 when there are 20 driveelectrode blocks B1 to B20 of the drive electrodes COML illustrated inFIG. 7 is illustrated. A driving signal applied block BAC indicates adrive electrode block B to which the touch driving signal VcomAC isapplied and the other drive electrode blocks B is supplied with novoltage and is in a so-called floating state in which potential is notfixed. The driving signal applied block BAC may indicate a driveelectrode block B to which the touch driving signal VcomAC is appliedand the display driving voltage VCOM may be applied to the other driveelectrode blocks B such that the potential thereof may be fixed. Thedrive electrode driver 14 illustrated in FIG. 1 selects the driveelectrode block B3 among the drive electrode blocks B to be subjected tothe touch detection operation illustrated in FIG. 13 and applies thetouch driving signal VcomAC to the drive electrode block B3. Then, thedrive electrode driver 14 selects the drive electrode block B4 among thedrive electrode blocks B illustrated in FIG. 14 and applies the touchdriving signal VcomAC to the drive electrode block B4. Then, the driveelectrode driver 14 selects the drive electrode block B5 among the driveelectrode blocks B illustrated in FIG. 15 and applies the touch drivingsignal VcomAC to the drive electrode block B5. As such, the driveelectrode driver 14 sequentially selects the drive electrode block B toapply the touch driving signal VcomAC to the selected drive electrodeblock B, and scans all of the drive electrode blocks B. The number ofdrive electrode blocks B is not limited to 20.

In the touch detection device 30, one of the drive electrode blocks Billustrated in FIGS. 13 to 15 corresponds to the drive electrode E1 inthe basic principle of the capacitive touch detection. In the touchdetection device 30, one of the touch detection electrodes TDLcorresponds to the touch detection electrode E2. The touch detectiondevice 30 detects a touch according to the above-mentioned basicprinciple. As illustrated in FIG. 12, the electrode patterns whichintersect each other form capacitive touch sensors in a matrix.Therefore, the touch detection device 30 scans the entire touchdetection surface to detect the position where an external proximityobject touches or approaches.

As illustrated in FIG. 16, the display unit 10 with a touch detectionfunction is driven such that the gate driver 12 time-divisionallyperforms line-sequential scanning for the scanning lines GCL, therebyperforming display scanning Scand. As illustrated in FIG. 16, thedisplay unit 10 with a touch detection function is driven such that thedrive electrode driver 14 sequentially selects the drive electrodeblocks B, thereby performing touch detection scanning Scant once for atime W1. As illustrated in FIG. 16, the touch detection scanning Scantis performed at a scanning speed which is two times that of the displayscanning Scand. As such, in the display device 1 with a touch detectionfunction, since the scanning speed of the touch detection operation ishigher than that of the display operation, it is possible to immediatelyrespond to the touch of an external proximity object which approachesfrom the outside and improve response characteristics to the touchdetection operation. The relation between the touch detection scanningScant and the display scanning Scand is not limited to that illustratedin FIG. 16. For example, the speed of the touch detection scanning Scantmay be more than two times the speed of the display scanning Scand, orit may be less than two times the speed of the display scanning Scand.

FIG. 17 is a block diagram illustrating switches according to theembodiment. As described above, the scanning lines GCL₁, GCL₂, GCL₃, . .. , GCL_(M) are provided in the display region Ad. The GCL_(M) indicatesthe last scanning line. The first gate driver 12A and the second gatedriver 12B each include, for example, the transmission circuits 61 andthe buffer circuits 62. The transmission circuits 61 constitute a shiftregister, and start an operation in response to the vertical start pulseVST. Each of the transmission circuits 61 is sequentially selected inthe vertical scanning direction in synchronization with the transmittedvertical clock pulse VCK, and the selected transmission circuits 61outputs a vertical selection pulse to the corresponding buffer circuit62.

The buffer circuit 62 receives the vertical selection pulse andtransmits a vertical scanning pulse Vgate which supplies a sufficientcurrent to drive the scanning line GCL by using a high-level potentialVGH and a low-level potential VGL and. The vertical scanning pulse Vgatewill be described below.

In a discharge switch SW, one end of a transistor is coupled to thescanning line GCL, the other end of the transistor is coupled to thelow-level potential VGL of the vertical scanning pulse, and a switchcontrol pulse GCK is input to a gate. Therefore, the discharge switch SWcan supply the low-level potential VGL of the vertical scanning pulse tothe scanning line GCL in response to the input of the switch controlsignal GCK. As such, the discharge switch SW is coupled to the end whichis opposite to a vertical drive circuit connection end of the scanningline GCL coupled to the first gate driver 12A or the second gate driver12B and can supply the same potential as that of the first gate driver12A or the second gate driver 12B.

The discharge switches SW include: a plurality of switches that areprovided close to the first gate driver 12A and are coupled to the endsopposite to the vertical drive circuit connection ends of the scanninglines GCL which are coupled to the second gate driver 12B through thedisplay region Ad; and a plurality of switches that are provided closeto the second gate driver 12B and are coupled to the ends opposite tothe vertical drive circuit connection ends of the scanning lines GCLwhich are coupled to the first gate driver 12A. The discharge switchesSW operate at the same time in operative association with each switchwhich is arranged close to the first gate driver 12A or each switchwhich is arranged close to the second gate driver 12B. Therefore, it ispossible to reduce the number of lines for the switch control signalrequired to operate the discharge switches SW. As a result, it ispossible to reduce the number of lines required to operate the dischargeswitches SW or the number of circuits for generating the switch controlsignal and narrow the frame Gd.

The pixel Pix or the sub-pixel SPix corresponds to an example of a“pixel” according to the preset disclosure. The display region Adcorresponds to an example of a “display region” according to the presetdisclosure. The frame Gd corresponds to an example of a “frame region”according to the preset disclosure. The drive electrode COML correspondsto an example of a “common electrode” according to the presetdisclosure. The scanning line GCL corresponds to an example of a“scanning line” according to the preset disclosure. The first gatedriver 12A and the second gate driver 12B correspond to an example of“first and second vertical drive circuits” according to the presetdisclosure. The source driver 13 corresponds to an example of a“horizontal drive circuit” according to the preset disclosure. Thedischarge switch SW corresponds to a “switch” according to the presetdisclosure.

1-1B. Operation and Effect

The operation and effect of the display device 1 with a touch detectionfunction according to the embodiment will be described. FIG. 18 is atiming chart illustrating a display operation period and an idle periodaccording to the embodiment. FIGS. 19 and 20 are circuit diagramsillustrating an example of the scanning line. FIG. 21 is a circuitdiagram illustrating an example of the scanning line according to theembodiment. FIG. 22 is a diagram illustrating a variation in thepotential of the scanning line according to the embodiment.

The operation of the display device 1 with a touch detection functionaccording to the embodiment will be described. As illustrated in FIG.18, the first gate driver 12A and the second gate driver 12Bsequentially output the pulse generated from the vertical start pulseVST and the vertical clock pulse VCK as the vertical scanning pulse andsupply the vertical scanning pulse to the scanning line GCL tosequentially select each row of the sub-pixels SPix. When a verticalsynchronization signal VSYNC is input, the first gate driver 12A and thesecond gate driver 12B alternately select the scanning line GCL from thefirst stage in a display operation period Pd (display operation periodPd1) and the source driver 13 performs a display operation of writingdisplay data up to an s-th stage (s is an integer equal to or greaterthan 2) of the scanning lines GCL through the signal lines SGL. Thedrive electrode driver 14 supplies the display driving voltage VCOM,which is a display voltage, to the drive electrode COML.

When identifying the high-level potential of a touch detection periodidentification signal TSHD, the first gate driver 12A and the secondgate driver 12B stop the transmission of the vertical scanning pulse,supply a lower-level potential VGL to the scanning lines GCL, and enteran idle period Pt (idle period Pt1). In the idle period Pt, the sourcedriver 13 stops the display operation of writing display data to thesub-pixels SPix through the signal lines SGL. Then, the drive electrodedriver 14 supplies the touch driving signal VcomAC to the driveelectrode COML of the display unit 10 with a touch detection function,on the basis of the control signal supplied from the control unit 11.The touch detection unit 40 detects whether the touch detection device30 is touched (in the contact or proximity state) on the basis of thecontrol signal supplied from the control unit 11 and the touch detectionsignal Vdet supplied from the touch detection device 30 of the displayunit 10 with a touch detection function, and calculates, for example,the coordinates of a touch point in the touch detection region when thetouch detection device 30 is touched.

When identifying the low-level potential of a touch detection periodidentification signal TSHD, the first gate driver 12A and the secondgate driver 12B resume the transmission of the vertical scanning pulse.When identifying the low-level potential of the touch detection periodidentification signal TSHD, the drive electrode driver 14 supplies thedisplay driving voltage VCOM, which is a display voltage, to the driveelectrode COML. For example, when the low-level potential of the touchdetection period identification signal TSHD is input, the first gatedriver 12A and the second gate driver 12B alternately select thescanning line GCL from an (s+1)-th stage in the display operation periodPd (display operation period Pd2) and the source driver 13 performs thedisplay operation of writing display data up to an (s+t)-th stage (t isan integer equal to or greater than 2) of the scanning lines GCL throughthe signal lines SGL.

Then, when identifying the high-level potential of the touch detectionperiod identification signal TSHD (Active), the first gate driver 12Aand the second gate driver 12B stop the transmission of the verticalscanning pulse, supply the lower-level potential VGL to the scanninglines GCL, and enter the idle period Pt (idle period Pt2). In the idleperiod Pt, the source driver 13 stops the display operation of writingdisplay data to the sub-pixels SPix through the signal lines SGL. Then,the drive electrode driver 14 supplies the touch driving signal VcomACto the drive electrode COML of the display unit 10 with a touchdetection function on the basis of the control signal supplied from thecontrol unit 11. The touch detection unit 40 detects whether the touchdetection device 30 is touched (in the contact or proximity state) onthe basis of the control signal supplied from the control unit 11 andthe touch detection signal Vdet supplied from the touch detection device30 of the display unit 10 with a touch detection function, andcalculates, for example, the coordinates of a touch point in the touchdetection region when the touch detection device 30 is touched.

When identifying the low-level potential of the touch detection periodidentification signal TSHD, the first gate driver 12A and the secondgate driver 12B resume the transmission of the vertical scanning pulse.When identifying the low-level potential of the touch detection periodidentification signal TSHD, the drive electrode driver 14 supplies thedisplay driving voltage VCOM, which is a display voltage, to the driveelectrode COML. For example, when the low-level potential of the touchdetection period identification signal TSHD is input, the first gatedriver 12A and the second gate driver 12B alternately select thescanning line GCL from an (s+t+1)-th stage in the display operationperiod Pd (display operation period Pd3) and the source driver 13performs the display operation of writing display data up to an(s+t+p)-th stage (p is an integer equal to or greater than 2) of thescanning lines GCL through the signal lines SGL.

Then, when identifying the high-level potential of the touch detectionperiod identification signal TSHD (Active), the first gate driver 12Aand the second gate driver 12B stop the transmission of the verticalscanning pulse, supply the lower-level potential VGL to the scanninglines GCL, and enter the idle period Pt (idle period Pt3). In the idleperiod Pt, the source driver 13 stops the display operation of writingdisplay data to the sub-pixels SPix through the signal lines SGL. Then,the drive electrode driver 14 supplies the touch driving signal VcomACto the drive electrode COML of the display unit 10 with a touchdetection function on the basis of the control signal supplied from thecontrol unit 11. The touch detection unit 40 detects whether the touchdetection device 30 is touched (in the contact or proximity state) onthe basis of the control signal supplied from the control unit 11 andthe touch detection signal Vdet supplied from the touch detection device30 of the display unit 10 with a touch detection function, andcalculates, for example, the coordinates of a touch point in the touchdetection region when the touch detection device 30 is touched.

As described above, the display device 1 with a touch detection functionaccording to the embodiment detects a touch in the idle period Pt inwhich display is stopped between the display operations (between thedisplay operation periods Pd). Therefore, it is possible to reduce aninfluence on display in the touch detection operation.

The first gate driver 12A (second gate driver 12B) illustrated in FIGS.19, 20, and 21 transmits a vertical scanning pulse Vgate, which is asquare wave formed by the high-level potential VGH and the low-levelpotential VGL, to the scanning line GCL_(s) in order to select each rowof the sub-pixels SPix in the display region Ad in the display operationperiod Pd illustrated in FIG. 22. It is more preferable that the idleperiod Pt illustrated in FIG. 22 be sufficiently temporally separatedfrom the rising edge and the falling edge of the vertical scanning pulseVgate before and after the idle period Pt.

The first gate driver 12A (second gate driver 12B) illustrated in FIG.19 is coupled to one end of the scanning line GCL_(s) in the extensiondirection. When a terminal coupled to the first gate driver 12A (secondgate driver 12B) is a near end (vertical drive circuit connection end)Ps, the terminal which is not coupled to the first gate driver 12A(second gate driver 12B) is a far end Pe. At the far end Pe of thescanning line GCL_(s), resistance Rgate and capacitor capacitance Cgateare more than those at the near end Ps of the scanning line GCL_(s) andthere is a difference in the time constant of a pulse, which is afunction of the product of the resistance Rgate and the capacitorcapacitance Cgate. At the far end Pe illustrated in FIG. 19, thedischarge switch SW is not provided, but only the capacitor capacitanceCgate is provided. FIG. 23 is a diagram illustrating the couplingcapacitance between the common electrode and the scanning line of thedisplay device.

As illustrated in FIG. 23, coupling capacitance Ccomgate is generatedbetween the scanning line GCL_(s) and the drive electrode COML which isa common electrode of the display device. Similarly, capacitance Ccomsigis generated between the signal line SGL_(n) and the drive electrodeCOML which is a common electrode of the display device. Further,capacitance Cpix is generated between the pixel electrode and the driveelectrode COML and the pixel signal Vpix is held therebetween. Asdescribed above, in the idle period Pt, the drive electrode driver 14supplies the touch driving signal VcomAC to the drive electrode COML.Therefore, in the idle period Pt illustrated in FIG. 22, the potentialof the drive electrode COML varies. In FIG. 22, the touch driving signalVcomAC, which is potential applied to the drive electrode COML, isschematically described as one square wave. However, the touch drivingsignal VcomAC may be a variation in a plurality of potentials such asthe AC square wave Sg illustrated in FIG. 6.

The low-level potential VGL is directly supplied to the near end Ps ofthe scanning line GCL_(s) illustrated in FIG. 19 in the idle period Pt.In contrast, the low-level potential VGL which is applied to the nearend Ps is applied to the far end Pe of the scanning line GCL_(s)illustrated in FIG. 19 through a plurality of resistors Rgate and aplurality of capacitor capacitances Cgate in the idle period Pt. Whenthe potential of the drive electrode COML is changed, an influence(coupling) occurs through the coupling capacitance Ccomgate and avariation (noise) may occur in the potential of the scanning lineGCL_(s). Since the low-level potential VGL is directly supplied to thenear end Ps of the scanning line GCL_(s), a variation in the potentialof the scanning line GCL_(s) through the coupling capacitance Ccomgateis suppressed. However, the potential of the far end Pe of the scanningline GCL_(s) illustrated in FIG. 19 may cause noise NP which is apotential variation illustrated in FIG. 22. The noise NP causes aleakage current Rq illustrated in FIG. 23 between the signal line SGLand the capacitance Cpix and an operation error may occur in the TFTelement Tr. As a result, the quality of the display region Ad maydeteriorate.

It is effective that the first gate driver 12A and the second gatedriver 12B which are arranged such that the scanning line GCL_(s) isinterposed therebetween in the extension direction of the scanning lineGCL_(s) supply the low-level potential VGL of the vertical scanningpulse Vgate from both ends of the scanning line GCL_(s) in order toreduce the influence of the noise NP of the scanning line caused by avariation in the potential of the drive electrode COML as a commonelectrode for display, as illustrated in FIG. 20. The distance of thefar end Pe of the scanning line GCL_(s) illustrated in FIG. 20 from thenear end Ps1 and the near end Ps2 of the scanning line GCL_(s) is halfthe distance of the far end Pe of the scanning line GCL_(s) illustratedin FIG. 19 from the near end Ps1 and the near end Ps2. Therefore, thetime constant of the scanning line GCL_(s) illustrated in FIG. 20 whichis affected by the resistance Rgate and the capacitor capacitance Cgatecan be about one-fourth of the time constant of the scanning lineGCL_(s) illustrated in FIG. 19. As a result, it is possible to improvethe quality of the display region Ad including the scanning line GCL_(s)illustrated in FIG. 20. However, the first gate driver 12A (second gatedriver 12B) is coupled to the end of each scanning line GCL_(s) andselects each row of the sub-pixels SPix in the display region Ad fromboth ends of the scanning line GCL_(s). Therefore, the number of TFTelements Tr in the first gate driver 12A (second gate driver 12B)increases and the area of the circuit increases. As a result, the sizeof the frame Gd increases.

In the display device 1 with a touch detection function according to theembodiment, as illustrated in FIG. 21, the first gate driver 12A (secondgate driver 12B) is coupled to one end of each scanning line GCL_(s) inthe extension direction. The terminal coupled to the first gate driver12A (second gate driver 12B) is the near end Ps, and the terminal whichis not coupled to the first gate driver 12A (second gate driver 12B) isthe far end Pe. The discharge switch SW is coupled to the far end Pe ofthe scanning line GCL_(s). As described above, the discharge switch SWis a circuit in which the number of transistor elements is less than thenumber of circuits forming the first gate driver 12A (second gate driver12B). Since the first gate driver 12A (second gate driver 12B) selectseach row of the sub-pixels SPix in the display region Ad from the nearend Ps of the scanning line GCL_(s), it is possible to reduce the numberof TFT elements Tr to be less than that in the first gate driver 12A(second gate driver 12B) illustrated in FIG. 20. When the number of TFTelements Tr is reduced, the area of the circuit is reduced and it ispossible to narrow the frame Gd.

The discharge switch SW supplies the low-level potential VGL of thevertical scanning pulse Vgate to the far end Pe of the scanning lineGCL_(s), in response to the input of the switch control signal GCK. Forexample, as illustrated in FIG. 18 or 22, when identifying thehigh-level potential of the touch detection period identification signalTSHD (Active), the COG 19 transmits the high-level potential (Active) ofthe switch control signal GCK to the discharge switch SW at the sametime or immediately after identifying the high-level potential of thetouch detection period identification signal TSHD. The switch controlsignal GCK may be transmitted from a circuit other than the COG 19, suchas the transmission circuit 61.

The low-level potential VGL is directly supplied to the near end Ps ofthe scanning line GCL_(s) illustrated in FIG. 21 in the idle period Pt.In addition, the low-level potential VGL is supplied from the dischargeswitch SW to the far end Pe of the scanning line GCL_(s) illustrated inFIG. 21 in the idle period Pt. When the potential of the drive electrodeCOML varies, an influence (coupling) occurs through the couplingcapacitance Ccomgate and a variation (noise) may occur in the potentialof the scanning line GCL_(s). However, since the low-level potential VGLis directly supplied to the near end Ps and the far end Pe of thescanning line GCL_(s), a variation in the potential of the scanning lineGCL_(s) through the coupling capacitance Ccomgate, that is, noise NQ issuppressed. The time constant affected by the resistance Rgate and thecapacitor capacitance Cgate can be about one-fourth of that of thescanning line GCL_(s) illustrated in FIG. 19 between the near end Ps andthe far end Pe of the scanning line GCL_(s) and the influence of noiseis suppressed. As such, in the idle period Pt, the scanning line GCL_(s)may be fixed to the low-level potential VGL and a variation in thepotential of the scanning line GCL_(s) through the coupling capacitanceCcomgate, that is, the noise NQ is suppressed.

As illustrated in FIG. 22, when identifying the low-level potential ofthe touch detection period identification signal TSHD, the COG 19transmits the low-level potential of the switch control signal GCK tothe discharge switch SW at the same time as the low-level potential ofthe touch detection period identification signal TSHD is identified orimmediately before the low-level potential of the touch detection periodidentification signal TSHD is identified. Therefore, the first gatedriver 12A (second gate driver 12B) can transmit the vertical scanningpulse Vgate from the near end Ps of the scanning line GCL_(s) in theextension direction and start the display operation period Pd.

The discharge switch SW may also give the same potential as that givenby the first gate driver 12A or the second gate driver 12B in atransient period from the start of the falling edge of the verticalscanning pulse Vgate applied to the scanning line GCL_(s) and toimmediately before the rising edge of the vertical scanning pulse Vgateapplied to the next scanning line GCL_(s+1) in the display operationperiod Pd. Thereby, the vertical scanning pulse Vgate applied to thescanning line GCL_(s) falls sharply and the falling edge of the verticalscanning pulse Vgate applied to the scanning line GCL_(s) can betemporally separated from the rising edge of the vertical scanning pulseVgate applied to the next scanning line GCL_(s+1). In this case, thedisplay device 1 with a touch detection function according to theembodiment supplies the switch control signal GCK to the dischargeswitch SW in each horizontal period (1H) of each stage. When the displaydevice 1 with a touch detection function according to the embodimentsupplies the switch control signal GCK to the discharge switch SW onlyin the idle period Pt to cause the discharge switch SW to operate, powerconsumption is about one-twentieth of that when the discharge switch SWis operated in both the display operation period Pd and the idle periodPt.

FIG. 24 is a cross-sectional view illustrating the schematiccross-sectional structure of a display unit with a touch detectionfunction according to a modification. In the display devices 1 with atouch detection function according to the above-described embodiment andthe modification, the liquid crystal display unit 20 using various modesof liquid crystal, such as FFS and IPS modes, and the touch detectiondevice 30 can be integrated into the display unit 10 with a touchdetection function. Alternatively, in the display unit 10 with a touchdetection function according to the modification illustrated in FIG. 24,the touch detection device may be integrated with various modes ofliquid crystal, such as a twisted nematic (TN) mode, a verticalalignment (VA) mode, and an electrically controlled birefringence (ECB)mode.

In the above-described embodiment, the display device in which thecapacitive touch detection device 30 is integrated with the liquidcrystal display unit 20 is described. However, the configuration is notlimited thereto. For example, a display device may be a device in whichthe capacitive touch detection device 30 is mounted on the liquidcrystal display unit 20. In a case of the display device in which thecapacitive touch detection device 30 is mounted on the liquid crystaldisplay unit 20, the drive electrode COML of the pixel substrate 2illustrated in FIG. 8 is a first drive electrode COML, a second driveelectrode COML is provided on the surface of the glass substrate 31 inthe counter substrate 3, and the first drive electrode COML iselectrically coupled to the second drive electrode COML. In this case,the above-mentioned configuration makes it possible to detect a touchwhile reducing the influence of external noise or noise transmitted fromthe liquid crystal display unit (corresponding to internal noise in theabove-described embodiment).

1-1C. Effect

As described above, the display device 1 with a touch detection functionaccording to the embodiment includes the discharge switch SW which iscoupled to the far end Pe opposite to the near end (vertical drivecircuit connection end) Ps of the scanning line GCL coupled to the firstgate driver 12A or the second gate driver 12B. The discharge switch SWgives the same potential as that given by the first gate driver 12A orthe second gate driver 12B in the idle period Pt in which the sourcedriver 13 stops the display operation of supplying the image signalVsig. Therefore, the display device 1 with a touch detection functionaccording to the embodiment can prevent an increase in the size of theframe Gd and the possibility of the leakage current Rq flowing betweenthe capacitor Cpix and the signal line SGL in the idle period Pt inwhich display is stopped between the display operations. As a result,the display device according to the embodiment can prevent deteriorationof the quality of the display region Ad. The display device 1 with atouch detection function according to the embodiment includes the driveelectrode COML which is given the driving signal VcomAC in the idleperiod Pt, the touch detection electrode TDL which forms capacitancetogether with the drive electrode COML, and the touch detection unit 40which detects the position of an approaching object on the basis of thedetection signal from the touch detection electrode TDL, and can detectan external proximity object which approaches the display region Ad fromthe outside.

1-2. Display Device

Some display devices without a touch detection function which perform adriving operation of changing a common electrode for display other thana display driving operation in an idle period in which display isstopped between the display operations. The display device 1 with atouch detection function has been described above, but the presetdisclosure is not limited to the display device with a touch detectionfunction. The following display device differs from the display device 1with a touch detection function in that the configuration for detectinga touch is not provided, but the liquid crystal display unit 20 and acontrol device are provided. The same components as those in theabove-described embodiment are denoted by the same reference numeralsand the description thereof will not be repeated.

FIG. 25 is a diagram illustrating a change in the potential of ascanning line according to the embodiment. FIG. 26 is a diagramschematically illustrating common potential inversion driving for twohorizontal periods. In the display device, when a DC voltage with thesame polarity is continuously applied to a liquid crystal element LC,the resistivity (specific resistance) of liquid crystal may deteriorate.

The display device inverts the polarity of the common potential of thedrive electrode COML, that is, the display driving voltage VCOM forevery two horizontal period in order to prevent deterioration of theresistivity (specific resistance) of liquid crystal, and inverts thepolarity of the pixel signals Vpix (VpixR, VpixG, and VpixB) in apredetermined cycle on the basis of the common potential. For example,as illustrated in FIG. 25, the polarity of the display driving voltageVCOM of the drive electrode COML is inverted for every two horizontalperiod and the polarity of the pixel signal VpixR is inverted in apredetermined cycle on the basis of the common potential. In this way,as illustrated in FIG. 26, the polarity of the pixel signals Vpix(VpixR, VpixG, and VpixB) applied to the sub-pixels SPix are alternatelychanged between the positive (+) polarity and the negative (−) polarityfor every two horizontal lines. As a result, the display device canprevent, for example, deterioration of the resistivity (specificresistance) of liquid crystal.

As illustrated in FIG. 23, the coupling capacitance Ccomgate isgenerated between the scanning line GCL_(s) and the drive electrode COMLwhich is a common electrode of the display device. Similarly, thecapacitance Ccomsig is generated between the signal line SGL_(n) and thedrive electrode COML which is the common electrode of the displaydevice. As illustrated in FIG. 25, the potential of the drive electrodeCOML varies in the idle period Pt in which the polarity of the displaydriving voltage VCOM of the drive electrode COML is inverted in everytwo horizontal periods. When the potential of the drive electrode COMLvaries, an influence (coupling) occurs through the coupling capacitanceCcomgate and a variation (noise) may occur in the potential of thescanning line GCL_(s). Since the low-level potential VGL is directlysupplied to the near end Ps of the scanning line GCL_(s), a variation inthe potential of the scanning line GCL_(s) through the couplingcapacitance Ccomgate is suppressed. However, the potential of the farend Pe of the scanning line GCL_(s) illustrated in FIG. 19 may cause thenoise NP which is a potential variation illustrated in FIG. 22. Thenoise NP may cause the leakage current Rq illustrated in FIG. 23 betweenthe signal line SGL and the capacitance Cpix. As a result, the qualityof the display region Ad may deteriorate.

In the display device according to the embodiment, as illustrated inFIG. 21, the first gate driver 12A (second gate driver 12B) is coupledto one end of the scanning line GCL_(s) in the extension direction. Theterminal coupled to the first gate driver 12A (second gate driver 12B)is the near end Ps, and the terminal which is not coupled to the firstgate driver 12A (second gate driver 12B) is the far end P. The dischargeswitch SW is coupled to the far end Pe of the scanning line GCL_(s). Thedischarge switch SW supplies the low-level potential VGL of the verticalscanning pulse Vgate to the far end Pe of the scanning line GCL_(s), inresponse to the input of the switch control signal GCK. For example, asillustrated in FIG. 25, the COG 19 transmits the high-level potential ofthe switch control signal GCK to the discharge switch SW in the idleperiod Pt. The switch control signal GCK may be transmitted from acircuit, such as the transmission circuit 61, other than the COG 19.

The low-level potential VGL is directly supplied to the near end Ps ofthe scanning line GCL_(s) illustrated in FIG. 21 in the idle period Pt.The low-level potential VGL is supplied from the discharge switch SW tothe far end Pe of the scanning line GCL_(s) illustrated in FIG. 21 inthe idle period Pt. When the potential of the drive electrode COMLvaries, an influence (coupling) occurs through the coupling capacitanceCcomgate and a variation (noise) may occur in the potential of thescanning line GCL_(s). However, in the display device according to theembodiment, since the low-level potential VGL is directly supplied tothe near end Ps and the far end Pe of the scanning line GCL_(s), avariation in the potential of the scanning line GCL_(s) through thecoupling capacitance Ccomgate, that is, noise NQ is suppressed. The timeconstant affected by the resistance Rgate and the capacitor capacitanceCgate can be about one-fourth of that of the scanning line GCL_(s)illustrated in FIG. 19 between the near end Ps and the far end Pe of thescanning line GCL_(s) and the influence of noise is suppressed.

After the polarity of the common potential is inverted as illustrated inFIG. 25, the COG 19 transmits the low-level potential of the switchcontrol signal GCK to the discharge switch SW. Then, the first gatedriver 12A (second gate driver 12B) can transmit the vertical scanningpulse Vgate from the near end Ps of the scanning line GCL_(s) in theextension direction and start the display operation period Pd.

The discharge switch SW may give the same potential as that given by thefirst gate driver 12A or the second gate driver 12B in a transientperiod from the start of the falling of the vertical scanning pulseVgate applied to the scanning line GCL_(s) and to immediately before therising of the vertical scanning pulse Vgate applied to the next scanningline GCL_(s+1) in the display operation period Pd. Thereby, the verticalscanning pulse Vgate applied to the scanning line GCL_(s) falls sharplyand the falling edge of the vertical scanning pulse Vgate applied to thescanning line GCL_(s) can be temporally separated from the rising edgeof the vertical scanning pulse Vgate applied to the next scanning lineGCL_(s+1). In this case, the display device according to the embodimentsupplies the switch control signal GCK to the discharge switch SW ineach horizontal period (1H) of each stage. When the display deviceaccording to the embodiment supplies the switch control signal GCK tothe discharge switch SW only in the idle period Pt to cause thedischarge switch SW to operate, power consumption is about half of thatwhen the discharge switch SW is operated in both the display operationperiod Pd and the idle period Pt.

1-2A. Effect

As described above, the display device according to the embodimentincludes the discharge switch SW which is coupled to the far end Peopposite to the near end (vertical drive circuit connection end) Ps ofthe scanning line GCL coupled to the first gate driver 12A or the secondgate driver 12B. The discharge switch SW gives the same potential asthat given by the first gate driver 12A or the second gate driver 12B inthe idle period Pt in which the source driver 13 stops a displayoperation of supplying the image signal Vsig to each sub-pixel Spixthrough the signal line SGL. Therefore, the display device according tothe embodiment can prevent an increase in the size of the frame Gd andthe possibility of a leakage current Rq flowing between the capacitorCpix and the signal line SGL in the idle period Pt, in which display isstopped, between the display operations. As a result, the display deviceaccording to the embodiment can prevent deterioration of the quality ofthe display region Ad. In the display device according to theembodiment, the polarity of the common potential applied to the driveelectrode COML, which is a common electrode, is switched in the idleperiod Pt. Therefore, it is possible to maintain the performance of theliquid crystal element LC.

Embodiments and modifications have been described above. However, thepreset disclosure is not limited thereto, and various modifications andchanges of the preset disclosure can be made.

2. Application Examples

Applications of the display device 1 with a touch detection functionaccording to the embodiment and modification will be described withreference to FIGS. 27 to 39. FIGS. 27 to 39 are diagrams illustratingexamples of electronic apparatuses to which the display device with atouch detection function or the display device according to theembodiment is applied. The display device 1 with a touch detectionfunction and the display device according to the embodiment and themodification can be applied to all fields of electronic apparatuses,such as televisions, digital cameras, notebook personal computers,portable terminal apparatuses including mobile phones, and videocameras. In other words, the display device 1 with a touch detectionfunction and the display device according to the embodiment and themodification can be applied to all fields of electronic apparatuseswhich display a video signal input from the outside or a video signalgenerated from the inside as an image or a video.

Application 1

The electronic apparatus illustrated in FIG. 27 is a television to whichthe display device 1 with a touch detection function and the displaydevice according to the embodiment and the modification are applied. Thetelevision includes, for example, a front panel 511 and a video displayscreen unit 510 including a filter glass 512. The image display screenunit 510 is the display device 1 with a touch detection function and thedisplay device according to the embodiment and the modification.

Application 2

The electronic apparatus illustrated in FIGS. 28 and 29 is a digitalcamera to which the display device 1 with a touch detection function andthe display device according to the embodiment and the modification areapplied. The digital camera includes, for example, a flash lightemitting unit 521, a display unit 522, a menu switch 523, and a shutterbutton 524. The display unit 522 is the display device 1 with a touchdetection function and the display device according to the embodimentand the modification.

Application 3

The electronic apparatus illustrated in FIG. 30 is the exterior of avideo camera to which the display device 1 with a touch detectionfunction and the display device according to the embodiment and themodification are applied. The video camera includes, for example, a mainbody unit 531, an object imaging lens 532 which is provided on the frontsurface of the main unit 531, a start/stop switch 533 for imaging, and adisplay unit 534. The display unit 534 is the display device 1 with atouch detection function and the display device according to theembodiment and the modification.

Application 4

The electronic apparatus illustrated in FIG. 31 is a notebook personalcomputer to which the display device 1 with a touch detection functionand the display device according to the embodiment and the modificationare applied. The notebook personal computer includes, for example, amain body 541, a keyboard 542 for inputting letters, and a display unit543 which displays images. The display unit 543 is the display device 1with a touch detection function and the display device according to theembodiment and the modification.

Application 5

The electronic apparatus illustrated in FIGS. 32 to 38 is a mobile phoneto which the display device 1 with a touch detection function and thedisplay device according to the embodiment and the modification areapplied. The mobile phone is, for example, formed by connecting an uppercasing 551 and a lower casing 552 with a connection portion (hingeportion) 553 and includes a display 554, a sub-display 555, a picturelight 556, and a camera 557. The display 554 or the sub-display 555 isthe display device 1 with a touch detection function and the displaydevice according to the embodiment and the modification.

Application 6

The electronic apparatus illustrated in FIG. 39 is a portableinformation terminal which is called a smart phone or a so-called tabletterminal that functions as a portable computer, a multi-functionalmobile phone, a portable computer which can perform voice communication,or a portable computer which can perform communication. The portableinformation terminal includes, for example, a display unit 562 which isprovided on the surface of a casing 561. The display unit 562 is thedisplay device 1 with a touch detection function and the display deviceaccording to the embodiment and the modification.

3. Aspects of Present Disclosure

The present disclosure includes the following aspects.

(1) A display device comprising:

a display region in which a plurality of pixels are arranged in amatrix;

a frame region outside the display region;

a common electrode that gives a common potential to the correspondingpixels;

a plurality of scanning lines that extend in a first direction in thedisplay region;

a plurality of signal lines that extend in a second direction in thedisplay region;

first and second vertical drive circuits that are arranged in the frameregion such that the scanning lines are interposed therebetween in thefirst direction, the first and second vertical drive circuits beingconfigured to alternately apply a vertical scanning pulse in the firstdirection to select each row of the pixels in the display region;

a horizontal drive circuit that performs a display operation ofsupplying an image signal to each of the pixels in the row selected bythe first vertical drive circuit or the second vertical drive circuitthrough the signal lines; and

a plurality of switches each of which is coupled to an end opposite to avertical drive circuit connection end of each scanning line which iscoupled to the first vertical drive circuit or the second vertical drivecircuit, wherein

the switches supply the same potential as that supplied to the scanningline by the first vertical drive circuit or the second vertical drivecircuit to the scanning line in an idle period in which the horizontal

(2) The display device according to (1), wherein

the switches supply a lower-level potential of the vertical scanningpulse to the scanning line which is coupled thereto.

(3) The display device according to (1), wherein

the switches include a plurality of switches which are arranged close tothe first vertical drive circuit and a plurality of switches which arearranged close to the second vertical drive circuit, and operate at thesame time in operative association with the plurality of switches closeto the first vertical drive circuit or the plurality of switches closeto the second vertical drive circuit.

(4) The display device according to (1), further comprising a touchdetection device configured to detect an external proximity object whichapproaches the display region from the outside, the touch detectiondevice including

-   -   (a) a drive electrode to which a driving signal is supplied in        the idle period,    -   (b) a touch detection electrode which forms capacitance together        with the drive electrode, and    -   (c) a touch detection unit which detects the position of an        approaching object on the basis of a detection signal from the        touch detection electrode.

(5) The display device according to (4), wherein

the drive electrode serves as the common electrode and supplies thecommon potential to each of the pixels when the display operation isperformed.

(6) The display device according to (1), wherein the polarity of thecommon potential supplied to the common electrode is switched in theidle period.

(7) A method of driving a display device including:

a display region in which a plurality of pixels are arranged in amatrix;

a frame region outside the display region;

a common electrode that gives a common potential to the correspondingpixels;

a plurality of scanning lines that extend in a first direction in thedisplay region;

a plurality of signal lines that extend in a second direction in thedisplay region;

first and second vertical drive circuits that are arranged in the frameregion such that the scanning lines are interposed therebetween in thefirst direction, the first and second vertical drive circuits beingconfigured to alternately apply a vertical scanning pulse in the firstdirection to select each row of the pixels in the display region;

a horizontal drive circuit that performs a display operation ofsupplying an image signal to each of the pixels in the row selected bythe first vertical drive circuit or the second vertical drive circuitthrough the signal lines; and

a plurality of switches each of which is coupled to an end opposite to avertical drive circuit connection end of each scanning line which iscoupled to the first vertical drive circuit or the second vertical drivecircuit, the method comprising:

the switches supplying the same potential as that supplied to thescanning line by the first vertical drive circuit or the second verticaldrive circuit to the scanning line in an idle period in which thehorizontal drive circuit stops the display operation.

(8) An electronic apparatus having a display device, the display devicecomprising:

a display region in which a plurality of pixels are arranged in amatrix;

a frame region outside the display region;

a common electrode that gives a common potential to the correspondingpixels;

a plurality of scanning lines that extend in a first direction in thedisplay region;

a plurality of signal lines that extend in a second direction in thedisplay region;

first and second vertical drive circuits that are arranged in the frameregion such that the scanning lines are interposed therebetween in thefirst direction, the first and second vertical drive circuits beingconfigured to alternately apply a vertical scanning pulse in the firstdirection to select each row of the pixels in the display region;

a horizontal drive circuit that performs a display operation ofsupplying an image signal to each of the pixels in the row selected bythe first vertical drive circuit or the second vertical drive circuitthrough the signal lines; and

a plurality of switches each of which is coupled to an end opposite to avertical drive circuit connection end of each scanning line which iscoupled to the first vertical drive circuit or the second vertical drivecircuit, wherein

the switches supply the same potential as that supplied to the scanningline by the first vertical drive circuit or the second vertical drivecircuit to the scanning line in an idle period in which the horizontaldrive circuit stops the display operation.

(9) A display device comprising:

a display region in which a plurality of pixels are arranged in amatrix;

a plurality of scanning lines that extend in a first direction in thedisplay region;

a plurality of signal lines that extend in a second direction in thedisplay region;

a vertical drive circuit that is coupled to first ends of the scanninglines and applies a vertical scanning pulse to the first ends to selecteach row of the pixels in the display region;

a horizontal drive circuit that performs a display operation ofsupplying an image signal to each of the pixels in the row selected bythe vertical drive circuit through the signal lines; and

a plurality of switches that are coupled to second ends of the scanninglines respectively, wherein

each of the switches supplies the same potential as that supplied to thefirst ends by the vertical drive circuit to the second end correspondingthereto in an idle period in which the horizontal drive circuit stopsthe display operation.

According to one aspect, a display device, a method of driving a displaydevice, and an electronic apparatus can suppress the noise of a scanningline while narrowing a frame.

What is claimed is:
 1. A display device comprising: scanning lines thatextend in a first direction; signal lines that extend in a seconddirection; first and second vertical drive circuits that are arrangedsuch that the scanning lines are interposed therebetween in the firstdirection, the first and second vertical drive circuits being configuredto alternately apply a vertical scanning pulse in the first direction toselect each of the scanning lines; and switches each having a first endand a second end, the first end being connected to a first Vertical GateLine (VGL) wiring to which a lower-level potential of the verticalscanning pulse is applied, the second end being connected to each of thescanning lines, wherein the switches connected to a same switch controlline are applied with a switch control signal.
 2. The display deviceaccording to claim 1, wherein the switches supply the lower-levelpotential to the scanning line to which the switches are coupled.
 3. Thedisplay device according to claim 1, wherein the switches includeswitches which are arranged close to the first vertical drive circuitand switches which are arranged close to the second vertical drivecircuit, and operate at the same time in operative association with theplurality of switches close to the first vertical drive circuit or theplurality of switches close to the second vertical drive circuit.
 4. Thedisplay device according to claim 1, further comprising a touchdetection device configured to detect an external proximity object whichapproaches the touch detection device from the outside, the touchdetection device including (a) a drive electrode to which a drivingsignal is supplied in an idle period in which an image signal is notapplied to the signal lines, (b) a touch detection electrode which formscapacitance together with the drive electrode, and (c) a touch detectionunit which detects a position of an approaching object on the basis of adetection signal from the touch detection electrode.
 5. The displaydevice according to claim 4, further comprising pixels arranged inmatrix and a common electrode that gives a common potential to thecorresponding pixels, wherein the drive electrode serves as the commonelectrode and supplies the common potential to each of the pixels whenthe image signal is applied to the signal lines.
 6. The display deviceaccording to claim 5, wherein polarity of the common potential isswitched in the idle period.
 7. The display device according to claim 1,wherein second VGL wirings are coupled to one of the first verticaldrive circuit and the second vertical drive circuit, and the second VGLwirings supply the lower-level potential to the scanning lines.
 8. Thedisplay device according to claim 7, wherein the second VGL wiringssupply the lower-level potential to the scanning lines in timingsdifferent from timings that the first VGL wirings supply the lower-levelpotential to the scanning lines.
 9. The display device according toclaim 7, wherein a first number is a number of the scanning lines towhich the first VGL wirings supply the lower-level potential at onetiming, a second number is a number of the scanning lines to which thesecond VGL wirings supply the lower-level potential to the scanninglines at one timing, and the first number and the second number aredifferent.
 10. The display device according to claim 1, wherein each ofthe first vertical drive circuit and the second vertical drive circuithas buffer circuits and transmission circuits, and a second VGL wiringis connected to each of the buffer circuit and supplies the lower-levelpotential to each of the scanning lines.
 11. A display devicecomprising: scanning lines that extend in a first direction; signallines that extend in a second direction; a vertical drive circuit thatis arranged such that the scanning lines are interposed therebetween inthe first direction, the vertical drive circuit being configured toalternately apply a vertical scanning pulse in the first direction toselect each of the scanning lines; and switches each having a first endand a second end, the first end being connected to a first Vertical GateLine (VGL) wiring to which a lower-level potential of the verticalscanning pulse is applied, the second end being connected to each of thescanning lines, wherein the switches connected to a same switch controlline are applied with a switch control signal.
 12. The display deviceaccording to claim 11, wherein the switches supply the lower-levelpotential to the scanning line to which the switches are coupled. 13.The display device according to claim 11, further comprising a touchdetection device configured to detect an external proximity object whichapproaches the touch detection device from the outside, the touchdetection device including (a) a drive electrode to which a drivingsignal is supplied in an idle period in which an image signal is notapplied to the signal lines, (b) a touch detection electrode which formscapacitance together with the drive electrode, and (c) a touch detectionunit which detects a position of an approaching object on the basis of adetection signal from the touch detection electrode.
 14. The displaydevice according to claim 13, further comprising pixels arranged inmatrix and a common electrode that gives a common potential to thecorresponding pixels, wherein the drive electrode serves as the commonelectrode and supplies the common potential to each of the pixels whenthe image signal is applied to the signal lines.
 15. The display deviceaccording to claim 14, wherein polarity of the common potentialsswitched in an idle period in which no image signal is applied to thesignal lines.
 16. The display device according to claim 11, whereinsecond VGL wirings are coupled to the vertical drive circuit, and thesecond VGL wirings supply the lower-level potential to the scanninglines.
 17. The display device according to claim 16, wherein the secondVGL wirings supply the lower-level potential to the scanning lines intimings different from timings that the first VGL wirings supply thelower-level potential to the scanning lines.
 18. The display deviceaccording to claim 16, wherein a first number is a number of thescanning lines to which the first VGL wirings supply the lower-levelpotential at one timing, a second number is a number of the scanninglines to which the second VGL wirings supply the lower-level potentialto the scanning lines at one timing, and the first number and the secondnumber are different.
 19. The display device according to claim 11,wherein the vertical drive circuit has buffer circuits and transmissioncircuits, and a second VGL wiring is connected to each of the buffercircuit and supplies the lower-level potential to each of the scanninglines.